A clockwork is the inner workings of either a mechanical clock

Clock

A clock is an instrument used to indicate, keep, and co-ordinate time. The word clock is derived ultimately from the Celtic words clagan and clocca meaning "bell". A silent instrument missing such a mechanism has traditionally been known as a timepiece...

 or a device that operates in a similar fashion. Specifically, the term refers to a mechanical device utilizing a complex series of gear

Gear

A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....

s.

A clockwork motor is a mechanically powered clockwork device powered by a mainspring

Mainspring

A mainspring is a spiral torsion spring of metal ribbon that is the power source in mechanical watches and some clocks. Winding the timepiece, by turning a knob or key, stores energy in the mainspring by twisting the spiral tighter. The force of the mainspring then turns the clock's wheels as it...

. Clockwork motor

Motor

Motor is a device that creates motion. It usually refers to an engine of some kind. It may also specifically refer to:*Electric motor, a machine that converts electricity into a mechanical motion...

s are generally manually energised using a key (wound up) via a ratchet device.
Often power for the device is stored within it, via a winding device that applies mechanical stress to an energy-storage mechanism such as a mainspring

Mainspring

A mainspring is a spiral torsion spring of metal ribbon that is the power source in mechanical watches and some clocks. Winding the timepiece, by turning a knob or key, stores energy in the mainspring by twisting the spiral tighter. The force of the mainspring then turns the clock's wheels as it...

, thus involving some form of escapement

Escapement

In mechanical watches and clocks, an escapement is a device that transfers energy to the timekeeping element and enables counting the number of oscillations of the timekeeping element...

; in other cases, hand power may be utilized.